YAMAHA oil injection article

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Found this one today, thought with some recent postings it would be good material.

http://www.bwbmag.com/output.cfm?id=942859

More than a mere convenience for boaters, automatic oil injection helps two-stroke outboards run at peak performance. When the system is functioning properly, the engine will produce less smoke, while resisting carbon buildup and spark-plug fouling. Because of its complexity, however, glitches sometimes cause rough-running engines, excessive smoking, oil leaks or even alarms to sound and lights to flash. While we cant address every possible situation for every outboard, well take this opportunity to examine Yamahas Precision Blend oil system. With proper troubleshooting techniques and a thorough understanding of how the system works, most problems are easily corrected.

Over the years, Yamaha has refined the electrical operation of the oil-transfer system to increase its reliability. Before you tear into any job, have the appropriate service manual, test equipment and tools needed. Naturally, you'll want to use common sense when working around gasoline, oil and electrical parts and be sure to observe all safety procedures outlined in the manual. A word to the wise: A few moments spent reading the instructions beforehand will save grief and time in the end.


Yamaha's system consists of two lubricant reservoirs, an electric pump, a crankshaft-driven metering pump, float-activated switches, filter screens, hoses and an electronic oil-control system. A 2.7-gallon reservoir (actually, a remote tank) mounted inside the boat contains the electric pump, filter and a fluid-level sensor switch. An oil hose from the remote tank attaches to the engine-mounted main tank, and a wiring harness connects it to the outboard's electronic circuitry. The main tank also contains a filter screen, float and three switches that send information to the oil-control unit. Two-stroke oil is fed via gravity through a hose on the bottom of the main tank to the crankshaft-driven oil pump, where it is metered to the engine.

LUBRICANT TRANSFER

All decisions about transferring oil (as well as sounding any alarms) are made by the electronic oil-control unit. On V-4 and older V-6 outboards, it consists of an external black box with a momentary toggle switch. In later V-6 models, Yamaha incorporated the switch and electronics into the CDI unit.

Located in the boat, the remote tank holds oil that is pumped to the powerhead as the engine demands. Mounted in a recess on the side of the tank, the electric oil pump receives the lubricant through a filter element and transfers it to the main tank, which is located on the powerhead. A float activates a switch (SW B) inside the reservoir when approximately 1-1/2 quarts remain. The switch signals the oil-controller to turn on the yellow warning LCD on the tachometer, and to stop the transfer of oil to the outboards main tank.
Inside the main tank, three float-activated switches inform the control unit when the tank is full, when to transfer more oil, and when to sound the alarm if the level drops too low.

As long as the remote tank contains enough oil, a green LCD lights up on the tachometer and the electric pump will transfer oil to the engine as needed. In the main tank, as oil is consumed and the level drops, a float triggers the middle switch (SW 2), which informs the control unit to turn on the electric transfer pump. The additional oil allows the float to rise up and initiate the upper switch (SW 1) to shut off the pump. In the event no lubricant is transferred and the oil level decreases enough for the float to pass the bottom switch (SW 3), the oil-control unit sounds a warning alarm, the red "no oil" LCD lights up, and the outboard slows to around 2000 rpm for its protection. This warning alerts the skipper that only one-third of a quart remains in the main tank.